.collapsibleList li {
    list-style-image: url('button.png');
    cursor: auto;
}

li.collapsibleListOpen {
    list-style-image: url('button-open.png');
    cursor: pointer;
    margin-bottom: 1em;
}

li.collapsibleListClosed {
    list-style-image: url('button-closed.png');
    cursor: pointer;
}